Hi Danish,
Thanks for the clarification.
As per the functionality, the system will also default the sender field to the user who is initiating the process. This user should obviously have the necessary access to initiate a process.
In the previous example, I was logged in with the same user, who deployed the process and also initiated the process instance.
Attached screenshots would shows the above point, wherein the sender is reflecting the process initiator.
Regards
Samik